Smoke detector and signal



1951 c. N. cAHusAc ET AL, 2,537,028

SMOKE DETECTOR AND SIGNAL 1 Filed Oct. 2, 1945 2 Sheets-Sheet l Jan. 9, 1951 c:.v N. cAHusAc ETAL. 5 2

SMOKE DETECTOR AND SIGNAL Filed Oct. 2, 1945 2 Sheets-Sheet 2 4 jvifi i 5 CLRRENCE NOEL C HHUSH AND FRHNK BHLLEN, 4&5] @p Patented J an. 9, 11951 SMOKE DETECTOR AND SIGNAL,

Clarence Noel Cahusac, Newark, and Frank B. Allen, Verona, N. J assignors to C-O-Two Fire Equipment 00., Newark, N. J a corporation of Delaware Application October 2, 1945, Serial No. 619,744

8 Claims. 1

This invention relates in general to apparatus for detecting and announcing the existence at a point remote from the apparatus, of a fluid having particles of matter suspended therein such as smoke; more particularly the invention contemplates such apparatus which is especially adapted for detecting the presence of smoke in the various compartments or rooms of airplanes, ships, railway cars, and buildings, and producing a signal, for example on the instrument board of an airplane, to ensure immediate warning of fires and prompt action to extinguish them.

The invention especially contemplates smoke detectors of the type wherein smoke from the compartment or space being protected is conducted through a casing in which is located apparatus responsive to the presence of the smoke, for example, smoke detectors like that described in our United States Patent No. 2,301,367 and an application Serial No. 604,892, filed July 13, 1945, which is now U. S. Patent 2,464,211, granted March 15, 1949, which include means for producing a beam of light, means for conducting a stream of smoke into said beam, and a photoelectric element located with respect to said light beam and the smoke stream to receive light rays reflected from suspended matter in said smoke.

Smoke detectors of this type heretofore have included pumps or other means for drawing or forcing the smoke from the space being protected through said casing, which requires the constant operation of motors with the attendant cost of installation, operation, maintenance and possibility of break-down of the motors or pumps.

A prime object of the present invention is to provide a smoke detector of the character described wherein the smoke shall be caused to flow in a novel and improved manner from the protected space into such relation to the light beam and the photoelectric element that light will be reflected from suspended matter in the smoke upon said photoelectric element.

Another object is to provide such a smoke detecting apparatus in which smoke shall be caused to flow through the casing of the apparatus by convection or thermal currents, induced either by the air currents in the protected space or by heat from a source such as an electric lamp from which the light beam is projected.

A further object is to provide a smoke detector which shall embody novel and improved features of construction whereby smoke may flow by convection or thermal currents through a casing in which the light beam and the photoelectric element are mounted and at the same time entry 2 of light from the protected space into said casing such as might cause false operation of the photoelectric element, shall be prevented.

Other objects, advantages and results of the invention will be brought out by the following description in conjunction with the accompanying drawings in which Figure 1 is a top plan View of a smoke detector embodying our invention.

Figure 2 is atop plan view of the smoke detector with the cover plate removed for clearness in illustration.

Figure 3 is a vertical longitudinal sectional view on the line 3-3 of Figure 2.

Figure 4 is a front elevation-a1 View of the detector illustrating a modification of the invention, with portions broken away and shown in section.

Figure 5 is a similar view illustrating another modification of the invention.

Figure 6 is a schematic longitudinal vertical sectional view through an airplane fuselage illustrating one manner of installing the smoke detecting apparatus therein, and s Figure '7 is a wiring diagram of the detecting and signalling circuit.

The invention is shown in conjunction with a detecting unit which comprises a casing l preferably having at least a removable top wall 2 and also having a partition 3 which divides the casing into a smoke compartment 4 and a compartment 5 for a light source 6 such as an incandescent lamp, said compartment 5 having openings or louvers l and 8 in its bottom and top walls for passage of air through the compartment. In the partition 3 is a lens system 9 through which light rays from the lamp 6 are directed into and longitudinally of the compartment 4 so that the light rays, represented by the broken lines, are projected in a parallel beam through the compartment 4.

At least one photoelectric element I0 is adjustably mounted on a bracket ll within the compartment 4 at one side of the light beam so as to be sensitive to light rays reflected from the suspended matter in the stream of fluid entering the casing. This photoelectric element may be of any suitable type, such as the current generating barrier layer type and preferably has a large flat rectangular exposed light sensitive surface I2 and is capable of generating sufficient current to operate an electrical responsive device such as a Sensitrol relay without amplification of the electricity. Preferably the light sensitive surface is exposed in close proximity to the outer boundaries of the light beam and is tilted obliquely with respect to the light beam so that said surface is inclined away from the light source as shown in Figure 2. Great sensitivity is thus obtained and at the same time the effect of stray light rays when no smoke is present in the compartment is substantially reduced.

'fhe photoelectric element H3 is connected in circuit with any suitable electrical responsive device, for example a micro-ammeter or, as shown, a Sensitrol relay l3 which maybe mounted by a frame 14 on the front wall of the casingwith its dial or face exposed through a window It in said casing wall; and said fSensitrol controls another circuit which may include ianydesired electrically operated device such as a signal lamp 16 located on the instrument panel 11, or a howler or audible signal I8 which may be located at any suitable point. The circuit for connecting the Sensitrol in circuit with a source of electricity, .said signals and the photoelectric elements are shown in Figure 7 and will belater described.

As hereinbefore indicated, the present invention isdirected to means for causing circulation of smoke or other 'fluid containing suspended matter from the source of the fluid or smoke through the detector casing Land Figures 1 to 3 inclusive illustrate one embodiment of the invention. As shown, the bottom wall l9-of the casing has a plurality of iQpeningsZD over each of which is a flange 2! for preventing ingress of light rays from one direction into thewcasing through the openings. These openings maybe in the well-known form of louvers, flanges 2| I project outwardly 'fromthe wall l9 and on the inside of the wall is a plate 22 which has aplurality of openings or slots 23 normally in register with the openings "23 and'each having an overhanging flange 24, corresponding to the flange 2!. The flanges 2| and 24 are so related to the openings 23 and 23 as to prevent theentry of any light rays into the casing from any'direction through the openings 29 and 23.

If desired the plate 22 may be longitudinally slidably mounted. so as to Vary the size of the passages through'the openings 29 and'23jan'd a finger-piece 22a may be connected to the plate and extend through a slot in the wall IQ of the casing for sliding the plate.

The top wall 24 of the casing'has a plurality of openings 25 in corresponding flanges' zfi similar to the openings and flanges 28 and' 2l respectively, the flanges projecting outwardly'from said wall; and on the inner side of said wallis mounted a plate 2'l corresponding to the plate 22 which has openings 28 and corresponding overhanging flanges'29. The flanges 26 and 29 are so related to the openings 25 and'28 as to prevent ingress of light rays into the casing from any direction.

With this construction, it will be'observed'that smoke or other fluid may flow into the'smoke compartment 4 through the openings '20 and 2-3 and outwardly from said compartment through 1 the openings 25 and 28. It will also be seen that this flow of fluid may be induced by convection, the hot air and smoke from any source of fire tending to rise by convection and 'fi-ow into the casing through the openings and 23,

through the light beam and past the photoelectric element It and thence outwardly and upwardly through the openings and 28. Thermal currents in the fluid in the-detecting compartment are produced by the radiant -energy 4 of the light beam and by heat transmitted through the walls of the smoke detecting compartment from the light source 6.

A modification of the invention is shown in Figure 4 where the circulation by convection may be caused solely by a source of heat other "thanfrom a fire and the'thermal currents resultvOf course, the heat from the lamp may be used .torsupplementrconvection currents caused by the 'heat fromthe" fire in the space being protected.

As shown, a hood 3!) is mounted on the top wall 24 of the'casingvl overlying and in spaced relationtothe louvers 8 and 26 so that the heat from the lamp-6-' will cause convection currents to flow upwardly and inwardly through the louvers l and upwardly and outwardly through the louvers 8 into the space between the hood 30 and the top wall 24 of the casing. The end of -the hood adjacent the lamp-is closed, 'while'the opposite end is open 'and thus the :hotair cur- ;rents will flow through the hood'out of the open :end thereofand will draw fluid such: assmoke :or :air out. of theismoke compartmentd through the louvers 2 6. The smoke may be allowed'to enter the compartment 4 through any-tsuitable :opening, but preferably through openings like :the :louvers 2 I.

In some cases it ma'y'ibe-desirable tomore :positively direct the smoke into the. smoke fcompartment, an'd'ifor this purpose we may'm'ount ia hollow frusto-pyramidal or frusto-conical collector 3! having its smaller endencircling the louvers or openingsinithe -bottom'wall of the casin and its 5 larger flaring downwardly l and 1 outwardly-from: the. casing. With this construction, itwillbe observedthat the smoke which otherwise *would flow directly upwardly past the ends of the casing I will be intercepted by'the collector3 land directed into the-louvers 2|, where- 'by -a larger'volume 'of smoke may be caused "to 'flow'through the smoke compartment.

In smoke detectingapparatus-ofthe specific charaeter describ'ed in our aforesaid "copending application, another photoelectric element 5 32 which may be o'f'the same general type as the element It is mounted-'bv'bolts" 33 ona transverse partition 3 3 on the casing with its rear "side directed'toward the light source and its light sensitive surface juxtaposed to an opening 35 reflector 36 and be dire'cted'therebythrough the opening -35 on"the light sensitive surface of the photoelectric element l9.

"To vary the'ext'ent '-of-= exposure of the photoelectric element 32 to said reflected light'rays, a shutteror baiileplate -39 extends across the opening 35 and "has connected thereto a nut Ml through which is threaded a screw 4| one end of which'is rotatably mounted in-a bracket-42 on the partition'34, while its other" end is connected-to an adjusting'head 43-whichis'rotatably mountedin -a plate Mon thefront wall of the casing l "and provided with'suitable'means for rotating itsuch askerfs --45"for a-screw driver.

The photoelectric element -H? is connected in circuit with the photoelectric-element l 0 and the Sensitrol" l3 in what is known as 'an"opposed parallel arrangement, or so that the photoelectric eflects of said elements are caused to operate in a compensating, difierential or opposing relationship; in other words, the electrodes of the element 32 are connected respectively to the opposite electrodes of the element (see Figure '2).

With this construction, initially the photoelectric cell circuit is so adjusted that the relay i3 or-other device will assume a normal condition, for example, to open the signal circuit, when no smoke is present in .the casing I. When smoke or other fluid containing suspended matter is caused to flow through the casing into the beam of light, some of the light rays will be reflected from the solid particles in the stream upon the photoelectric cell I 0 whereupon the relay or other device l3 will be actuated by the current in the photoelectric cell circuit, for example, to close the signal circuit. In this connection it may be well to point out that the relay l3 has a pointer or swingable contact arm 46 which is responsive to current in the photoelectric cell circuit and normally is spaced from a fixed contact 46a but is actuated into engagement with said contact when the photoelectric cell circuit is energized.

It will be observed that the cells In will be continuously somewhat afiected by stray light rays from the beam even when no smoke is present in the compartment 4, and the cell will be further afiectecl by slight variations in the intensity or candle power of the light source 6, which without some means to prevent it will result in irregular or unsteady operation of the Sensitrol I 3. By rotating the screw 4|, the shutter 39 may be adjusted to vary the amount of light reflected from the reflector 36 through the opening 35 upon the balancing cell .32, and thus when no smoke is present in the compartment 4, the efiect of the light on the cell I0 may be balanced by the effect of the light on the cell 32 whereby a steady and normal setting of the Sensitrol pointer 46 may be obtained.

The photoelectric cells I9 and 32, the light source 6, the sensitive relay l3. the smoke alarm signals [6 and I8 and a trouble lamp 50 may be connected in a circuit in different Ways and one possible circuit arrangement is shown in Fig. '7 of the drawings. The reference character 41 designates generally a source of electric power one terminal 41a of which is grounded, while another terminal 48 is connected to a terminal 49a of a double-throw, double-pole toggle switch 49. The photoelectric cells 19 and 32 are connected in opposition with a relay coil 55 of the relay [3. Contacts 46 and 46a of the relay 13 are normally in the open position when no smoke is present in the smoke compartment. Contact 46a is connected with ground while contact 46 is connected with an electro-magnetic coil 54 of a power relay 54a. The other side of the coil 54 is connected to the supply wire 48. Thus, when contacts 45 and 46a of the sensitive relay l3 are closed, the coil 54 is energized bringing together contacts 52 and 52a. Contact 52 is connected to the positive supply wire 48 While contact 52a is connected to one side of the smoke alarm lamp l6 and thence to ground. A wire 52b connects contact 52a with midpoint 49d of the double-throw, double-pole toggle switch 49 to one side of the howler i 8 and thence to ground. Trouble relay 53a has its electro-magnetic coil 53 connected in series with the lamp 6 and the power supply 41 and has normally open contacts 5| and 5m, contact 51a is connected to ground while contact 5| is connected through midpoint 496 of the double-throw, double-pole toggle switch 49 to one side of the trouble lamp 50 and thence to ground. Relay 53a is used to give a trouble signal in the event lamp 6 should burn out. The double-throw, double-pole toggle switch 49 has an unused contact 49b and is normally connected through contacts 49d and 490 to the howler [8 which may be disconnected while the circuit is being tested or in the event a smoke signal has been given. When thrown in its downward position, switch midpoint 49e is connected to terminal 49a thereby continuously energizing the trouble lamp 50 to indicate that the toggle switch 49 is not in its normal operating position.

In the event smoke is present in the compartment 4, and light is reflected to the surface of the detecting cell 10, the output of the cell is increased to cause relay I3 to operate and bring contacts 46 and 46a, together to cause the power relay 54a to become energized and bring its contacts 52 and 52a together to energize the smoke signal lamp l6 and to sound the howler [8. In the event the lamp 6 should burn out, the coil 53 of relay 53a is ole-energized permitting its contacts to come together to complete a circuit to energize the trouble lamp 59.

It will be clear to those skilled in the art that the panel I1, indicator casing and the various signals and relays may be mounted in any desired locations but Figure 6 shows one possible arrangement of the parts of the smoke detecting and signaling system in an airplane.

In Figure 6 the instrument panel I1 is mounted in the pilots cabin, while the detector casing I is mounted on a partition 5'! which divides the pilots cabin or cockpit from the main portion of the fuselage and the openings or louvres at the bottom of the casing are exposed within said main portion so that any smoke that may be generated in said compartment will pass into said casing and cause operation of the signal.

Certain features of the apparatus disclosed herein are claimed in a co-pending application owned by the same assignee, Serial No. 74,341, filed February 3, 1949, as a continuation in part of Serial No. 604,892, filed July 13, 1945.

While we have shown and described our invention as embodied in certain details of construction it should be understood that this is primarily for illustrating the principles of the now preferred embodiment of the invention and that the structural details may be modified or changed and the apparatus may be used in other places than airplanes, all within the spirit and scope of the invention.

What we claim is:

1. A device for detecting the presence of suspended matter in a fluid comprising a casing having a detecting compartment and a light source compartment positioned adjacent each other in the horizontal plane and separated by a partition, a lens carried by the partition for projecting a beam of light from the light source through the detecting compartment, photo-electric means responsive to variations in the light in the detecting compartment, the casing having a plurality of apertures therein to provide inlet and outlet means for the circulation of "fluid through each of the compartments, louver means for preventing the entry of exterior light through the apertures into the detecting compartment,

and battle means extending over the outlet aper- 'tures'of the both compartments, whereby heated fluid from the light source compartment .is :conducted past the apertures of the detecting compartment to aid the circulation 0f the :fluid through the detecting compartment.

2. A device for :detecting the presence of suspending matter in a fluid comprising a casing having a detecting compartment and a .light source compartment, means for projecting a; beam of light through the detecting compartment and adapted to provide a source of heat in the light compartment, photo-electric means adapted to respond to variations in the .light in the detecting "compartment resulting "from the presence of suspended matter in the fluid, the

casing havin a plurality of apertures providing inlet and outlet means for the circulation of fluid through the detecting compartment and through the light compartment, light obstructing means for preventing the entry of exterior light through the apertures into the detecting compartment, and a conduit for conducting heated fluid from the light compartment past the outlet apertures of the detecting compartment to .aid the circulation of the fluid therethrough.

3. A device for detecting the presence of suspended matter in a fluid comprising a casing having a detecting compartment and a light source compartment, means for projecting a beam of light through the detecting compartment and adapted to provide a source of heat in the light compartment, photo-electric means adapted to respond to variations in the light in the detecting compartment caused by the presence of suspended matter in the fluid, the casing having inlet and outlet means for the circulation of fluid through each of the compartments, and a conduit for conducting heated fluid from the light compartment past the outlet of the detecting compartment to aid the circulation of the fluid through the detecting compartment.

4. A device for detecting the presence of suspended matter in a fluid comprising a casing L.

having a detecting compartment, means for projecting light through at least a portion of the detecting compartment, means providing a source of heat, photo-electric means responsive to variations in the light in the detecting compartment caused by the presence of suspended matter in the fluid, the casing having inlet and outlet means for the detecting compartment, and conduit means in fluid communication with the source of heat whereby fluid heated thereby is conducted .past the outlet of the detecting compartment to aidthe circulation therethrough.

5. A device for detecting the presence of suspended matter in a fluid comprising a casing having a detecting compartment with an inlet and outlet for the passage of the fluid therethrough, means for projecting light through at least a portion of the detecting compartment, means responsive to the presence of suspended matter in the fluid, and a source of heat to pro- Vide convection currents in the fluid to aid its 8 circulation through the detecting "compartment. 6. -A casing for a device for detecting the presence of suspended matter in a flui'd, the casing-having a detecting compartment and a light source compartment each with a plurality of apertures for the circulation of the fluid there- "through, light obstructing means for preventing the entry of exterior light into the detecting compartment, and conduit means in fluid communication with the outlet apertures of both compartments whereby the movement of the fluid through the light compartment aids the movement of fluid through :the detecting compartment.

'7. A device for detecting the presence of suspended matter in a fluid comprising a casing having 'a detecting compartment and a light source compartment positioned adjacent each other and separated by a partition, light transmitting means in the partition for projecting a beam of light from the light source .into the detecting compartment, photoelectric means responsive to variations in the light in the detecting compartment resulting from the presence "of suspended matter in fluid therein, the casing having a pluralityof openings into the detecting "compartment to :provide inlet and outlet means for the circulation of fluid therethrough by thermal circulation, and light bafiie means, the openings into the detecting compartment occupyin a large proportion of the area of 'the walls of the detecting compartment for the easy inlet and outlet of the fluid by thermal circulation.

8. A device .for detecting the presence of suspended matter in a fluid comprising a casing having a detecting compartment and a light source compartment positioned adjacent each other and separated by a partition, lens means carried by the partition for projecting a beam of light from the light source through the detecting compartment, photoelectric means responsive to variations in the light in the detecting compartment resulting from the presence of suspended matter in fluid therein, the casing having a plurality of openings into the detecting compartment to provideinlet and outlet means for the circulation of fluid therethrough by thermal circulation, and inner and outer louvers for the openings to prevent practically any rays of exterior light from entering through the openings and impinging upon the photoelectric means.

CLARENCE NOEL CAI-IUSA'C.

FRANK B. ALLEN.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PA'IENTS- Number Name Date 892,241 Freise June 30, 1908 1,256,740 Steiger Feb. 19, 1918 1,487,898 Stolp Mar. 25, 1924 1,828,894 Freyga-ng Oct. 27, 1931 2,232,169 Di-ller Feb. 18, 1941 2,267,319 Benning Dec. 23, 1941 

